Automatic chemistry analyzer

ABSTRACT

An automatic chemistry analyzer is provided having a high throughput and a high reliability. The analyzer uses nephelometric and turbimetric analyzers to analyze a wide variety of parameters within liquid samples typically generated in, for example, a large medical testing laboratory. The machine employs a unique probe and stirring rod assembly mounted at a slight angle with one another using rack and pinion assemblies so that the lower end of the probe and the lower end of the stirring rod are in very close proximity to one another. This feature allows the machine to be used in unusually small reaction cuvettes. The analysis machine also includes an onboard control sample so that the machine can be programmed to periodically calibrate its analyzing equipment during the course of normal operation. The machine also includes a sample station carousel having retainer clips for retaining a sample container rack which is constructed to retain a bar-coded card containing information regarding reagents used in the machine. A bar code reader located proximate to the sample carousel reads the bar-coded reagent information into the controller.

FIELD OF THE INVENTION

This invention generally relates to the field of automated clinicalchemical analyzers, and specifically to compact automated chemicalanalyzers using a nephelometer.

BACKGROUND OF THE INVENTION

A number of different automated clinical chemical analyzers are known inthe art. Such analyzers range from simple, largely manually-operatedinstruments to highly complex, nearly fully automated instruments. Eachanalyzer has its own particular performance characteristics related tothe number of different tests ("menu") that the analyzer can perform andthe number of samples that the analyzer can process in a given period oftime ("throughput").

As sophisticated and efficient as are many of today's automatedanalyzers, several problems continue to exist. First and foremost isthroughput capacity. Every second which can be saved in the analysistime of a single sample means millions of dollars in savings of preciousmedical resources. Therefore, there is continuous pressure on analyzermanufacturers to increase throughput. The automated analyzers of theprior art are quite fast, but not fast enough.

An additional problem in the prior art is cost of operation. Mostautomated analyzers of the prior art use relatively large reactioncontainers ("cuvettes") which require an excessive amount of expensivereagent materials. *

Still another problem in the prior art is the amount of time that anoperator must spend inputting data and instructions into the analyzer.This diminishes throughput and causes excessive manpower expenses.

Still another problem related to throughput is the necessity of priorart analyzing machines which use a nephelometric analyzer toperiodically shut down operations to calibrate the nephelometer.

Finally, there is a problem regarding throughput vacuum drain systemsused in automatic analyzers of the prior art. Such vacuum drain systemsare generally wasteful with respect to the use of vacuum. Such wasteresults in the use of excessively large vacuum usage and may decreasethroughput of the analyzer.

Accordingly, there is a need for an automated clinical chemical analyzerwhich has greater throughput than prior art analyzer modules, requiresless manpower to operate, is more reliable and is more efficient. **

SUMMARY OF THE INVENTION

The invention satisfies these needs. The invention is a device fordetermining at least one parameter of a liquid sample comprising:

(a) a body;

(b) a motorized sample station disposed within the body, the samplestation being sized and dimensioned to retain a plurality of samplecontainers and having a sample extraction site, the sample station beingmovable within the body such that, when the sample station retains aplurality of sample containers, individual sample containers canalternatively be moved to and away from the sample extraction site;

(c) a motorized reagent station disposed within the body, the reagentstation being sized and dimensioned to retain a plurality of reagentcontainers and having a reagent extraction site, the reagent stationbeing movable within the body such that, when the reagent stationretains a plurality of reagent containers, individual reagent containerscan alternatively be moved to and away from the reagent extraction site;

(d) a motorized random access analyzing station disposed within thebody, the random access analyzing station being sized and dimensioned toretain a plurality of cuvettes and having a cuvette mixing site, acuvette washing site, a random access analyzing station analyzing siteand an analyzer disposed proximate to the random access analyzingstation analyzing site for determining at least one parameter of asample disposed within the cuvettes, the random access analyzing stationbeing movable within the body such that, when the random accessanalyzing station retains a plurality of cuvettes, individual cuvettescan alternatively be moved to and away from (1) the cuvette mixing site,(2) the cuvette washing site and (3) the random access analyzing stationanalyzing site;

(e) a sample probe arm assembly attached to the body, the sample probearm assembly including (1) a sample probe arm, (2) a hollow sample probehaving an internal chamber, an open lower end and an open upper end and(3) an elongate rotatable sample stirring rod having a lower end and anupper end, the lower end of the sample stirring rod including a samplestirring rod paddle attached thereto, the sample probe and the samplestirring rod being disposed generally vertically in close proximity toone another, the sample probe being vertically movable between a lowersample probe position and an upper sample probe position, the samplestirring rod being movable of the sample probe between a lower samplestirring rod position and an upper sample stirring rod position, thesample probe and sample stirring rod being disposed within the sampleprobe arm assembly such that, when the sample probe is at the lowersample probe position and the sample stirring rod is at the lower samplestirring rod position, the sample probe arm being movable between afirst sample probe arm position wherein the sample probe is immediatelyabove the sample extraction site and a second sample probe arm positionwherein the sample probe is immediately above the cuvette mixing site;

(f) a sample probe positioning motor for moving the sample probe betweenthe lower sample probe position and the upper sample probe position;

(g) a sample stirring rod positioning motor for moving the samplestirring rod between the lower sample stirring rod position and theupper sample stirring rod position;

(h) a sample stirring rod rotating motor for rotating the samplestirring rod;

(i) a sample probe pressure altering assembly for alternatively applyinga positive pressure and a negative pressure to the interior chamber ofthe sample probe;

(j) a reagent probe arm assembly attached to the body, the reagent probearm assembly including (1) a reagent probe arm, (2) a hollow reagentprobe having an internal chamber, an open lower end and an open upperend and (3) an elongate rotatable reagent stirring rod having a lowerend and an upper end, the lower end of the reagent stirring rodincluding a reagent stirring rod paddle attached thereto, the reagentprobe and the reagent stirring rod being disposed generally verticallyin close proximity to one another, the reagent probe being verticallymovable between a lower reagent probe position and an upper reagentprobe position, the reagent stirring rod being movable of the reagentprobe between a lower reagent stirring rod position and an upper reagentstirring rod position, the reagent probe and reagent stirring rod beingdisposed within the reagent probe arm assembly such that, when thereagent probe is at the lower reagent probe position and the reagentstirring rod is at the lower reagent stirring rod position, the reagentprobe arm being movable between a first reagent probe arm positionwherein the reagent probe is immediately above the reagent extractionsite and a second reagent probe arm position wherein the reagent probeis immediately above the cuvette mixing site;

(k) a reagent probe positioning motor for moving the reagent probebetween the lower reagent probe position and the upper reagent probeposition;

(l) a reagent stirring rod positioning motor for moving the reagentstirring rod between the lower reagent stirring rod position and theupper reagent stirring rod position;

(m) a reagent stirring rod rotating motor for rotating the reagentstirring rod;

(n) a reagent probe pressure altering assembly for alternativelyapplying a positive pressure and a negative pressure to the interiorchamber of the reagent probe;

(o) a cuvette wash station attached to the body, the cuvette washstation including at least one motorized hollow cuvette wash stationprobe having an internal chamber, an open lower end and an open upperend, the cuvette wash station being disposed such that the cuvette washstation probe is immediately above the cuvette washing site; and

(p) a cuvette wash station probe supply and disposal assembly foralternatively (1) providing pressurized washing liquid from a source ofwashing liquid to the cuvette wash station probe for washing a cuvettedisposed within the random access analyzing station at the cuvettewashing site and (2) providing a negative pressure to the interiorchamber of the cuvette wash station probe for removing waste liquidsfrom a cuvette disposed within the random access analyzing station atthe analyzing site and for transferring such waste liquids to a suitabledisposal site.

Preferably, on each probe arm the distance between the probe and thestirring rod at their respective lowermost positions is between about1.7 and about 5.3 mm, more preferably between about 1.7 and about 3.5mm, most preferably between about 1.7 and about 3 mm.

Also, it is preferably that on each probe arm, the probe and thestirring rod be vertically movable independently of one another.

Preferably, each probe and stirring rod are attached to their probe armby a rack and pinion assembly for raising and lowering the probe andstirring rods. This feature allows for independent operation of theprobe and stirring rod while providing that the lower tip of the probeand stirring rod (at their lowermost positions) are very close to oneanother. This, in turn, allows the use of smaller reaction containersrequiring a minimum of expensive reagents.

In a preferred embodiment, the sample station comprises a rotatingsample carousel having an exterior wall with a retainer assembly forretaining a card displaying bar-coded information on the exterior wall.This allows a bar code reader disposed within the device to readbar-coded information regarding the reagent containers used in thedevice.

In another preferred embodiment, the sample station comprises aplurality of dilution sections, each having a plurality of dilutioncups. This feature allows the device to minimize the use of expensivereagents.

In still another preferred embodiment, the cuvette wash probe supply anddisposal assembly includes a waste trap assembly comprising (a) a wastetrap reservoir, (b) a waste collector bowl disposed below the waste trapreservoir, (c) a vertically disposed connector conduit for connectingthe waste trap reservoir in fluid communication with the waste collectorbowl, the connector conduit having an uppermost lip over which wasteliquids within the waste trap reservoir can spill over into the wastecollector bowl, (d) a connector conduit check valve for preventing theupward flow of liquids and pressurized air within the connector conduitfrom the waste collector bowl to the waste trap reservoir, (e) an inletport in the upper portion of the waste trap reservoir for receivingwaste liquid from the cuvette wash station probe, (f) an outlet port inthe bottom of the waste collector bowl for draining liquid within thewaste collector bowl to a suitable waste disposal facility via a drainconduit, (g) a drain conduit check valve disposed within the drainconduit to prevent liquids to flow into the waste collector bowl via thedrain conduit, (h) a level sensor for sensing the level of liquid withinthe waste collector bowl and emitting a corresponding level sensorsignal, (i) a switch assembly for alternatively applying pressure andvacuum to the waste collector bowl, (j) a waste trap controller forreceiving the level sensor signal from the level sensor and therewithcontrolling the switching assembly to allow the application of vacuumand pressure to the waste collector bowl in such a way that (i) when thelevel of liquid within the waste collector is below a preselected setpoint, vacuum is applied to the waste collector bowl to draw wasteliquid from the waste trap reservoir and (ii) when the level of liquidwithin the waste collector is at the preselected set point, pressure isapplied to the waste collector bowl to blow down waste liquid within thewaste collector bowl to the drain conduit.

The invention is also a method for analyzing a plurality of liquidsamples using the device described above.

The invention is also a chemical test reagent kit for use in anautomated testing machine having an internal bar code reader. The kitcomprises at least one container containing reagent and a bar code cardcontaining bar coded information regarding the reagent. The bar codecard is sized and dimensioned to be read by the internal bar code readerof an automated testing machine.

The invention provides significant improvements over the prior art byreducing reagent costs and operating expenses while increasingthroughput, accuracy and reliability.

DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription, appended claims and accompanying drawings where:

FIG. 1 is a schematic plan view of an automated analyzing machine havingfeatures of the invention;

FIG. 2 is a front view of an automated analyzing machine having featuresof the invention;

FIG. 3 is a perspective view of a sample carousel having features of theinvention;

FIG. 4A is a perspective view of a dilution section having features ofthe invention;

FIG. 4B is a plan view of the dilution section of FIG. 4A;

FIG. 4C is a cross-sectional side view of the dilution section shown inFIG. 4B, taken along line 4C--4C;

FIG. 4D is a bottom side view of the dilution container shown in FIGS.4A-4C;

FIG. 5A is a perspective view of a reaction cuvette module useful in theinvention;

FIG. 5B is a cross-sectional side view of the reaction cuvette moduleshown in FIG. 5A;

FIG. 6A is a perspective view of a sample probe arm assembly havingfeatures of the invention;

FIG. 6B is a cut-away view of the sample probe arm assembly shown inFIG. 6A;

FIG. 6C is a front view of a sample stirring rod useful in theinvention;

FIG. 6D is a side view of the sample stirring rod shown in FIG. 6C;

FIG. 7A is a perspective view of a reagent probe arm assembly havingfeatures of the invention;

FIG. 7B is a cut-away view of the reagent probe arm assembly shown inFIG. 7A;

FIG. 7C is a front view of a reagent stirring rod useful in theinvention;

FIG. 7D is a side view of the reagent stirring rod shown in FIG. 7C;

FIG. 8 is a perspective view of a cuvette wash station useful in theinvention;

FIG. 9A is an exploded view of a waste trap assembly having features ofthe invention;

FIG. 9B is a cross-sectional view of the fully assembled waste trapassembly shown in FIG. 9A;

FIG. 9C is a cross-sectional side detail view of a valve useful in thewaste trap assembly shown in FIGS. 9A and 9B;

FIG. 9D is a plan view of a flexible desk useful in the waste trapassembly shown in FIGS. 9A-9C; and

FIG. 10 is a perspective view of a sample container rack having featuresof the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion describes in detail one embodiment of theinvention and several variations of that embodiment. This discussionshould not be construed, however, as limiting the invention to thoseparticular embodiments. Practitioners skilled in the art will recognizenumerous other embodiments as well. For a definition of the completescope of the invention, the reader is directed to the appended claims.

FIGS. 1 and 2 show an automated analyzing machine 10 having features ofthe invention. The machine 10 comprises a body 12, a sample station 14,a reagent station 16 and a random access analyzing station 18.

The body 12 is generally a cabinet providing a housing for the variousoperative components used in the analyzing machine 10. The body 12 istypically made from a lightweight metal such as a lightweight sheetsteel. The body 12 can include a canopy (not shown) for fully enclosingthe operative components of the machine 10.

The sample station 14 is sized and dimensioned to retain a plurality ofsample containers 20. The sample station 14 has at least one sampleextraction site 22.

The sample station 14 preferably comprises a revolving sample carousel24 as illustrated in FIG. 3. Typically, the sample carousel 24 is madefrom a lightweight metal or molded plastic. The sample carousel 24 ispreferably sized and dimensioned to retain a plurality of samplecontainers 20, one or more diluent containers 26, and a plurality ofdilution sections 28.

In the embodiment shown in the drawings, the sample carousel 24comprises a carousel retainer assembly 40 for retaining a samplecontainer rack 30 on the exterior wall 32 of the sample carousel 24.Such retainer assembly 40 can be slots as shown in the embodimentillustrated in the drawings.

The sample rack 30 preferably comprises a sample container rack retainerassembly 39 for retaining a card 37 displaying bar-coded information onthe forward portion 41 of the sample container rack 30. Such samplecontainer rack retainer assembly 39 can be resilient clips as shown inthe embodiment illustrated in FIG. 10. However, many other ways ofattaching the bar-coded card 37 to the forward portion 41 of the samplecontainer rack 30 can also be used as well, including clamps, clips,prongs, snaps, buttons, hook and loop fasteners, pins, etc. It ispreferable that the sample container rack retainer assembly 39 allowsthe operator to quickly and easily attach and later de-attach a bar codecard 37 from the forward portion 41 of the sample container rack 30,most preferably without the use of tools.

In this embodiment, each sample container rack 30 houses nine individualsample containers 20 in a generally upright disposition.

The sample carousel 24 shown in FIG. 3 has four diluent containerretention locations 36 and four dilution section retention locations 38.The dilution sections 28 each comprise a plurality of dilution cups 42as shown in FIGS. 4A-4C. Typically, each dilution section 28 is madefrom a molded plastic. Preferably, each dilution section 28 is easilyinstalled and removed from the sample carousel 24 for ease of cleaning.It is also preferable that the dilution sections 28 be easily andquickly installed into and deinstalled from the sample carousel 24without use of tools. The embodiment shown in the drawings has resilientnodes 44 which allow the dilution sections 28 to snap fit in thedilution section retention locations 38.

Each dilution cup 42 holds between about 0.01 and about 1.0 millilitersof liquid. As shown in FIG. 4C, each dilution cup 42 is tapered at thebottom to form a dilution cup narrow well 46 so that small amounts ofliquid within the dilution cup 42 puddle within the narrow well andthereby remain easily extractable from the dilution cup 42. Eachdilution cup narrow well 46 typically can retain between about 10microliters and about 100 microliters. This feature minimizes reagentwaste. This feature is especially important where the dilution cups 42are made from a plastic material which is hydrophobic. In such cases,small amounts of liquid within the dilution cups 42 tend to bead insteadof puddling, making it difficult to extract the liquid from the dilutioncup 42.

The sample carousel 24 is movable by a rotating motor (not shown) suchthat each sample container 20 disposed on the sample carousel 24 can bealternatively positioned under and moved away from the one sampleextraction site 22.

Preferably, the sample station 14 further comprises a sample station barcode reader 47 for reading bar-coded information on the samplecontainers 20 within the sample station 14 and/or on a bar code card 37disposed on the forward portion 41 of the sample container rack 30.

The reagent station 16 is sized and dimensioned to retain a plurality ofreagent containers 48 and has at least one reagent extraction site 50. Aparticularly useful reagent container 48 usable in the machine of theinvention is described in detail in pending U.S. Pat. application Ser.No. 08/675,586, entitled "Reagent Cartridge", which is filedcontemporaneously herewith and which is also incorporated herein byreference in its entirety. The reagent station 16 is movable within thebody such that individual reagent containers 48 disposed within thereagent station 16 can be alternatively moved to and away from thereagent extraction site 50.

Like the sample station 14, the reagent station 16 preferably comprisesa rotatable reagent carousel 52, typically made from a lightweight metalor molded plastic. The reagent carousel 52 is rotated by a reagentstation motor (not shown).

Preferably, the reagent station 16 is refrigerated, such as to atemperature of about 15° C. Such refrigeration preserves reagent lifeand minimizes reagent evaporation.

Preferably, the reagent station 16 further comprises a reagent stationbar code reader 53 for reading bar-coded information on reagentcontainers 20 within the reagent station 16 and/or on the exterior ofthe reagent carousel 24.

The random access analyzing station 18 is sized and dimensioned toretain a plurality of reaction cuvettes 54 of the type commonly known inthe nephelometric and turbimetric arts. The random access analyzingstation 18 comprises at least one cuvette mixing site 56, one randomaccess analyzing station analyzing site 58 and a cuvette washing site60.

Like the sample station 14 and the reagent station 16, the random accessanalyzing station 18 preferably comprises a rotatable carousel 62 whichis rotated by a random access analyzing station motor (not shown).

In the embodiment shown in the drawings, the reaction cuvettes 54 aredisposed in cuvette modules 64, each cuvette module 64 containing threeindividual cuvettes 54. The cuvette modules 64 are shown in FIGS. 5A and5B. Each cuvette module 64 has prongs 66 to facilitate firm attachmentto the random access analyzing station carousel 62. To minimize the costof expensive reagent, it is important that the cuvettes 54 be made assmall as practically possible.

In most applications, it is preferable that the random access analyzingstation 18 be operatable at a fixed elevated temperature, such as about37° C. To accomplish this, the random access analyzing station 18preferably includes means for circulating heated air upwardly throughthe random access analyzing station 18.

The random access analyzing station 18 further comprises a random accessanalyzing station analyzer 68 which is disposed proximate to the randomaccess analyzing station analyzing site 58 for determining at least oneparameter of a sample disposed within a cuvette 54 within the randomaccess analyzing station 18. In a preferred embodiment, the randomaccess analyzing station analyzer 68 is a nephelometer and turbidimetercombination. Such a combination is well-known in the art. A detaileddescription of a typical nephelometer and turbidimeter combination isset forth, for example, U.S. Pat. No. 5,296,195, which is incorporatedherein by reference in its entirety. A particularly useful nephelometerand turbidimeter combination useful in the analysis machine of theinvention is described in pending U.S. Pat. application Ser. No.08/674,780, entitled "Nephelometer and Turbidimeter Combination", whichis filed contemporaneously herewith and which is incorporated herein byreference in its entirety.

In a typical nephelometer and turbidimeter combination, there is a firstlight source 70 disposed proximate to the random access analyzingstation analyzing site 58 for directing a first beam of light through acuvette 54 disposed at the random access analyzing site 58 to a firstlight receptor 72. In a preferred embodiment, this first light source 70is a visible diode laser emitting light at a wave length between about600 and about 850 nm. Preferably, a second light source 74 is alsodisposed proximate to the random access analyzing station analyzing site58 for directing a second beam of light through a cuvette 54 disposed atthe random access analyzing site 58 to a second light receptor 76. In apreferred embodiment, this second light source 74 is a light emittingdiode capable of emitting light at a wave length between about 850 andabout 1050 nm. Both first and second light receptors 72 and 76 measurethe amount of scattered light as the first and second light beams 70 and74 are projected through the cuvette 54. In the embodiment shown in FIG.1, the first light receptor 72 is disposed below the reaction cuvette tomeasure the amount of light scattered at a 90° angle with respect to thefirst beam of light. As is well-known in the art, such scattering oflight can be accurately correlated with one or more specific parametersof the liquid within the cuvette 54.

Preferably, the random access analyzing station 18 further comprises anonboard control sample 78. Such onboard control sample 78 allows theuser to program the machine to automatically calibrate the random accessanalyzing station analyzer 68 during normal operation of the machine 10.This feature maximizes accuracy and reliability over similar machines ofthe prior art. This feature also increases throughput by eliminating theneed to periodically shut down the machine 10 to calibrate the randomaccess analyzing station analyzer 68. A particularly useful onboardcontrol sample usable in the invention is described in detail in pendingU.S. Pat. application Ser. No. 08/675,587, entitled "Non-Liquid ScatterStandard", which is filed contemporaneously herewith and which isincorporated herein by reference in its entirety.

The analysis machine 10 of the invention further comprises a sampleprobe arm assembly 80 such as shown in FIGS. 6A-6D. The sample probe armassembly 80 includes a sample probe arm 82, a hollow sample probe 84 anda rotatable sample stirring rod 86. The sample probe 84 has an internalchamber 88, an open lower end 90 and an open upper end 91. A sampleprobe pressure altering assembly 92 is provided to alternatively placepressure or a vacuum on the internal chamber 88. Preferably, thepressure altering assembly 92 comprises a syringe 94.

The sample probe 84 is disposed generally vertically in the sample probearm 82 and is movable by a sample probe motor 96 between a lower sampleprobe position and an upper sample probe position.

The sample stirring rod 86 has a lower end 98, an upper end 100 and astirring rod paddle 102. The sample stirring rod 86 is also disposedgenerally vertically in the sample probe arm 82 and is movable by asample stirring rod motor 104 between a lower sample stirring rodposition and an upper sample stirring rod position. The sample stirringrod is operatively rotated by a sample stirring rod rotating motor 105.

Preferably, the raising and lowering of the sample stirring rod 86 isindependent of the raising and lowering of the sample probe 84. Thisprovides speed and flexibility over important similar devices in theprior art which can only raise and lower the stirring rod 86 at the sametime that the probe 84 is raised and lowered.

Preferably, the sample stirring rod 86 and the sample probe arm 84 areboth raised and lowered using a rack and pinion assembly 106. Such rackand pinion assembly 106 allows the sample probe 84 and the reagent probe86 to be mounted close enough to one another to achieve the closeproximities of their respective lower ends 90 and 98 describedimmediately below.

The sample probe 84 and the sample stirring rod 86 are disposed withinthe sample probe arm 82 at a slight angle with respect to one another.Preferably, this angle α is between about 2.4° and about 2.6°. Thesample probe 84 and the sample stirring rod 86 are angled towards oneanother so that, when both the sample probe 84 and the sample stirringrod 86 are at their respective lower positions, the distance between thelower end 90 of the sample probe 84 and the lower end 98 of the samplestirring rod 86 is between about 1.7 mm and about 5.3 mm, morepreferably between about 1.7 mm and about 3.5 mm, most preferablybetween about 1.7 mm and about 3 mm. By structuring the sample probe 84and the sample stirring rod 86 so as to be so close to one another attheir respective lower positions 90 and 98, the sample probe 84 andsample stirring rod 86 can effectively be used within reaction cuvettes54 which are much smaller than those used in prior art analyzingmachines. The ability to use such small reaction cuvettes 54 results insignificant reagent savings to the operator. It also allows the operatorto conduct clinical analyses with very small samples.

The device of the invention further comprises a reagent probe armassembly 108 such as shown in FIGS. 7A-7D. The reagent probe armassembly 108 includes a reagent probe arm 110, a hollow reagent probe112 and a rotatable reagent stirring rod 114. The reagent probe 112 hasan internal chamber 116, an opened lower end 118 and an open upper end120. A reagent probe pressure altering assembly 122 is provided toalternatively place pressure or a vacuum on the internal chamber 116.Preferably, the pressure altering assembly comprises a syringe 124.

The reagent probe 112 is disposed generally vertically in the reagentprobe arm 110 and is movable by a reagent probe motor 126 between alower reagent probe position and an upper reagent probe position.

The reagent stirring rod 114 has a lower end 128, an upper end 130 and astirring rod paddle 132. The reagent stirring rod 114 is also disposedgenerally vertically in the reagent probe arm 110 and is movable by areagent stirring rod motor 132 be between a lower reagent stirring rodposition and an upper reagent stirring rod position. As is the case withrespect to the sample probe 84 and the sample stirring rod 86, it ispreferable that the raising and lowering of the reagent stirring rod 114be independent of the raising and lowering of the reagent probe 112.

It is also preferable that the reagent stirring rod 114 and the reagentprobe 112 be raised and lowered using a rack and pinion assembly 134.Such rack and pinion assembly 134 allows the reagent probe 112 and thereagent stirring rod 114 to be mounted close enough to one another toachieve the close proximities at their lower ends 118 and 128 describedimmediately below.

Like the sample probe 84 and the sample stirring rod 86, the reagentprobe 112 and reagent stirring rod 114 are disposed within the reagentprobe arm 110 at a slight angle with respect to one another. Preferably,this angle β is between about 2.4° and about 2.6°. The reagent probe 112and the reagent stirring rod 114 are angled towards one another for thesame reason that the sample probe 84 and the sample stirring rod 86 areangled towards one another: that is to provide for a convergence of thelower ends 118 and 128 of the reagent probe 112 and the reagent stirringrod 114 to a distance between about 1.7 mm and about 5.3 mm, morepreferably between about 1.7 and about 3.5 mm, most preferably betweenabout 1.7 and about 3 mm. This close proximity of the lower ends 118 and128 of the reagent probe 112 and the reagent stirring rod 114 allow theuse of very small reaction cuvettes 54.

Preferably, both the sample probe arm 82 and the reagent probe arm 108comprise level controllers (not shown) for determining the elevation ofthe probes 84 and 112 and/or the stirring rods 86 and 114 relative to aliquid level.

The machine of the invention 10 further comprises a cuvette wash station130 attached to the body. The cuvette wash station 130 includes at leastone hollow cuvette wash station probe 132 having an internal chamber134, an open lower end 137 and an open upper end 139. The cuvette washstation 130 is disposed such that the cuvette wash station probe 132 isimmediately above the cuvette washing site 60.

The cuvette wash station probe 132 is movable by a cuvette wash stationmotor (not shown) between a lower cuvette wash station probe positionand an upper cuvette wash station probe position.

In the embodiment shown in FIG. 8, the cuvette wash station probe 132comprises two concentrically disposed cuvette wash station probes 132aand 132b. One probe 132 is used to evacuate the contents of a cuvetteand transmit such contents to a suitable disposal site 135. The otherprobe 132 is used to provide the cuvette with a washing solution.

The device of the invention further comprises a cuvette wash stationprobe supply and disposal assembly 136 for alternatively (1) providingpressurized washing liquid from a source of washing liquid to thecuvette washing station probe 132 for washing a cuvette 54 disposed atthe cuvette washing site 60 and (2) providing a negative pressure to theinterior chamber 134 of the cuvette wash station probe 132 for removingwaste liquids from a cuvette 54 disposed within analyzing site 60 andfor transferring such waste liquids to a suitable disposal site 135.

A preferred wash station probe supply and disposal assembly 136comprises a waste trap assembly 138 shown in FIGS. 9A-9D. The waste trapassembly 138 comprises a waste trap reservoir 140 and a waste collectorbowl 142 disposed below the waste trap reservoir 140. A verticallydisposed connector conduit 144 connects the waste trap reservoir 140 influid communication with the waste collector bowl 142. The connectorconduit 144 has an uppermost lip 146 over which waste liquids whichcollect within the waste trap reservoir 140 spill over into the wastecollector bowl 142. The connector conduit 144 has a connector conduitcheck valve 148 for preventing the upward flow of liquids andpressurized air within the connector conduit 144 from the wastecollector bowl 142 to the waste trap reservoir 140.

The waste trap reservoir 140 has an inlet port 150 in the upper portionof the waste trap reservoir 140 for receiving waste liquid from thecuvette wash station 130. The waste collector bowl 142 has an outletport 152 in the bottom of the waste collector bowl 142 for drainingliquid within the waste collector bowl 142 to a suitable waste disposalfacility via a drain conduit 154. The drain conduit 154 has a drainconduit check valve 156 to prevent liquids from flowing back into thewaste collector bowl 142 via the drain conduit 154.

A level sensor 158 is disposed within the waste collector bowl 142 forsensing the level of liquids within the waste collector bowl 142 andemitting a corresponding level sensor signal. In operation, the wastetrap reservoir 140 is operatively connected to a source of vacuum. Also,the waste collector bowl 142 is operatively connected via a switch 160to a source of vacuum and to a source of pressurized air.

The waste trap assembly 138 further comprises a waste trap controller(not shown) for receiving the level sensor 158 signal from the levelsensor and using that signal to control the application of a vacuum andpressure to the waste collector bowl in the following way: (i) when thelevel of liquid within the waste collector bowl 142 is below apreselected set point, vacuum is applied to the waste collector bowl 142to draw waste liquid from the waste trap reservoir 140 and (ii) when thelevel of liquid within the waste collector bowl 142 is at thepreselected set point, pressure is applied to the waste collector bowl142 to blow down waste liquid within the waste collector bowl 142 to thedrain conduit 154.

The waste trap assembly connector conduit check valve 148 preferablycomprises an inlet conduit 162, a valve seat 164 disposed within theinlet conduit 162 and in fluid tight communication therewith, an outletconduit 166 disposed below the valve seat 164 and in fluid tightcommunication therewith and a plug 168 loosely disposed within the valveseat 164 such that (1) when the pressure within the inlet conduit isequal to or greater than the pressure within the outlet conduit 166, theplug 168 is not held tightly against the valve seat 164 so as to allowliquid waste within the inlet conduit 162 to gravitate into the outletconduit 166 and (2) when the pressure within the inlet conduit 162 isless than the pressure within the outlet conduit 166, the plug 168 isheld tightly against the valve seat 164 so as to prevent liquid wastewithin the inlet conduit 162 from gravitating into the outlet conduit166 and to prevent pressurized air in the outlet conduit 166 fromflowing through the inlet conduit 164 into the waste trap reservoir 140.

Preferably, the plug 168 is a flexible disk as shown in the drawings.The flexible disk has at least one central aperture 170 which is off-setfrom the inlet conduit 162.

Preferably, the waste trap 138 assembly further comprises (a) a vacuumsource inlet port 172 disposed in the waste trap reservoir 140, thevacuum source inlet port 172 being connectable to a source of vacuum,(b) a three way valve 174 having a common port 176, a normally open port178 and a normally closed port 180, (c) a first pressure source conduit181 connected in fluid tight communication between the common port 176and the waste collection bowl 142, (d) a second pressure source conduit182 connected in fluid tight communication between the normally openport 178 and the waste trap reservoir 140, and (e) a third pressuresource conduit 184 connected in fluid tight communication between thenormally closed port 180 and a source of air pressure.

This waste trap assembly 138 provides significant advantages over priorart waste trap assemblies. The waste trap assembly 138 of the inventionrequires only one vacuum storage reservoir 140 and one vacuum pump.Moreover, a wash cycle need not be interrupted for liquid wasteevacuations. Also, no external waste pump is required as is generallyrequired by prior art systems. This is because the waste trap assembly138 of the invention relies on air pressure to drive the waste out ofthe assembly. Some prior art systems also use pressurized air to forcewaste out of a waste trap assembly. However, such systems are wastefulof vacuum since each time the reservoir level signals for the three-wayvalve to switch, the entire vacuum contents of the reservoir arereplaced by pressurized air to force waste to the pump. This cansignificantly slow down operation of the machine since replenishing thevacuum can take 16 seconds and more. Moreover, a relatively large vacuumpump is required.

Preferably, the analyzing machine 10 of the invention further comprisesa controller 186 for controlling the operation of the motors, analyzersand bar code readers. Preferably, the controller 186 includes a digitalcomputer which is also programmed to receive the results from theanalyzer 68 and report those results to the operator in an efficientformat.

In operation, the operator of a preferred embodiment of the analysismachine loads the reagent station 16 with premixed reagent from a kit.The kit includes one or more reagent containers 48 containing premixedreagent and a bar code card having bar-coded information thereonregarding the reagent within the kit.

After loading the reagent containers 48 into the reagent station 16, theoperator places the bar-coded card 37 from the reagent kit on theforward portion 41 of the sample container rack 30 using the samplecontainer rack retainer assembly 40. The operator instructs the samplestation bar code reader 47 to read into the controller the bar-codedinformation contained on the bar-coded card 37. The operator thenremoves the bar-coded card 37 from the sample container 30.

The operator then loads the sample carousel 24 with sample containers 20containing samples to be analyzed. The sample containers 20 are loadedinto sample container racks 30 and the sample container racks 30 areattached to the exterior perimeter of the sample carousel 24. A labelcontaining bar-coded information regarding the identity of each of thesamples and the analyses to be run on each of the samples is attached toeach sample container 20. The operator then places diluent containers 26in the sample carousel 24 and places clean dilution sections 28 in thesample carousel 24. The operator then engages the machine 10 whichcarries out the following steps automatically.

The sample carousel 24 is rotated, making frequent stops. Whenever acontainer 20 is disposed in front of the sample station bar code reader47, the bar code reader 47 reads the bar-coded information on the labelon the sample container 20 and passes that information along to thecontroller 186.

The sample probe arm 82 moves the sample station probe 84 to a positionimmediately above the sample extraction site 22. The sample probe 84 islowered from its upper probe position until the sample probe levelcontroller senses the fact that the sample probe 84 is below the surfaceof the sample within the sample container 20 positioned at the sampleextraction site 22.

The sample probe pressure altering assembly 92 is then caused to draw avacuum in the sample probe internal chamber 88. This, in turn, causessample within the sample container 20 to be drawn into the sample probeinternal chamber 88. The sample probe 84 is then raised to its upperposition and the sample probe arm 82 rotates to a position over one ofthe dilution cups 42. The sample probe 84 is again lowered into thedilution cup 42 and the sample probe pressure altering assembly 92causes the sample within the sample probe 84 to be discharged into thedilution cup 42.

The sample probe arm 82 then rotates the sample probe 84 to a positionimmediately above one of the diluent containers 26 in the sample station14. The sample probe 84 is lowered from its upper position to a positionbelow the surface of the diluent in the diluent container 26 as sensedby the sample probe level controller. The pressure altering assembly 92causes a vacuum to be drawn within the sample probe internal chamber 88and diluent is drawn into the sample probe 84. The sample probe 84 isthen raised to its upper position and the sample arm rotates the sampleprobe 84 to a position immediately above one of the dilution cups 42.The sample probe 84 is lowered into the dilution cup 42 and the pressurealtering assembly 92 pressures the diluent out of the sample probe 84and into the dilution cup 42.

The sample stirring rod 86 is then lowered into the dilution cup 42 andthe sample stirring rod rotating motor 105 is engaged to mix the sampleand the diluent.

Next, the sample probe 84 is again lowered into the dilution cup 42 andthe diluent-sample mixture is drawn into the sample probe 84. The sampleprobe arm 82 then rotates the sample probe 84 to a position immediatelyabove the cuvette 54 at the cuvette mixing site 56, the sample probe 84is lowered into the cuvette 54, and the diluent-sample mixture isexpelled from the sample probe 84 into the cuvette 54 by the sampleprobe pressure altering means 92.

Immediately before or after these steps, the controller 186 causes thereagent probe arm 110 to maneuver immediately above the appropriatereagent container 48 within the reagent extraction site 22 and thereagent probe 112 is lowered into the reagent container 48 and aquantity of reagent is drawn into the reagent probe 112. The reagentprobe 112 is then raised to its upper position and the reagent arm 110rotates the reagent probe 112 over the cuvette 54 at the cuvette mixingsite 56. The reagent probe 112 is then lowered into the cuvette 54 andthe reagent is discharged into the cuvette 54.

At this point, either the sample stirring rod 86 (or the reagentstirring rod 114 depending upon which stirring rod is immediately abovethe cuvette mixing site at this point in time) is lowered into thecuvette 54 and the rotating motor is engaged to agitate thereagent-sample mixture with the stirring rod paddle 102. After mixing,the stirring rod 86 is retracted to its upper position.

The controller 186 then causes the random access analyzing stationcarousel 62 to rotate the cuvette 54 having the reagent-sample mixturepast the random access analyzing station analyzing site 58. At thisanalyzing site 58, the random access analyzing station analyzer 68analyzes the contents of the cuvette 54 and transmits that informationto the controller 186. Preferably, the controller 186 causes the cuvette54 to pass through the random access analyzing station analyzing site 58on numerous occasions and instructs the analyzer 68 to analyze thecontents on each of those numerous occasions. By making numerousanalyses of the same reagent-sample mixture, the results ultimatelyreportable by the controller 186 are therefore very precise in nature.

After the contents of the cuvette 54 are analyzed, the random accessanalyzer carousel 62 is rotated so that the cuvette 54 is immediatelybelow the cuvette washing site 60. At the cuvette washing site 60, thecuvette wash station probe 132 is lowered into the cuvette 54 and thecontents of the cuvette 54 are extracted out of the cuvette 54 and sentto suitable disposal using the cuvette wash probe supply and disposalassembly 136. The cuvette 54 is then washed with pressurized washingliquid and that liquid is also sent to disposal using the cuvette washprobe supply and disposal assembly 136. The cuvette 54 is then clean andready for another analysis operation.

The controller 186 is preferably programmed to keep track of a largenumber of reaction cuvettes 54 in various stages of the analysisprocess. The controller 186 causes the random access analyzing stationcarousel 62 to rotate with great rapidity, moving any of the largenumber of active cuvettes 54 to the various cuvette sites for one ormore of the various operations described above. In this way, theanalyzing machine 10 can carry out a large number of analyses in a verysmall amount of time.

Periodically during normal operation of the machine, the controller 186causes the random access analyzing station analyzer 68 to analyze thecontents of the onboard control sample 78. If the results of thisanalysis suggests that the analyzer 68 is out of calibration, theanalyzer 68 is automatically recalibrated.

The invention provides significant improvements over the prior art byreducing reagent costs and operating expenses while increasingthroughput, accuracy and reliability.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the preferred versions containedherein.

What is claimed is:
 1. A device for determining at least one parameterof a liquid sample, the device comprising:(a) a body; (b) a motorizedsample station disposed within the body, the sample station being sizedand dimensioned to retain a plurality of sample containers and having asample extraction site, the sample station being movable within the bodysuch that, when the sample station retains a plurality of samplecontainers, individual sample containers can alternatively be moved toand away from the sample extraction site; (c) a motorized reagentstation disposed within the body, the reagent station being sized anddimensioned to retain a plurality of reagent containers and having areagent extraction site, the reagent station being movable within thebody such that, when the reagent station retains a plurality of reagentcontainers, individual reagent containers can alternatively be moved toand away from the reagent extraction site; (d) a motorized random accessanalyzing station disposed within the body, the random access analyzingstation being sized and dimensioned to retain a plurality of reactioncuvettes and having at least one cuvette mixing site, a cuvette washingsite, a random access analyzing station analyzing site and an analyzerdisposed proximate to the random access analyzing station analyzing sitefor determining at least one parameter of a sample disposed within thecuvettes, the random access analyzing station being movable within thebody such that, when the random access analyzing station retains aplurality of cuvettes, individual cuvettes can alternatively be moved toand away from (1) the cuvette mixing site, (2) the cuvette washing siteand (3) the random access analyzing station analyzing site; (e) a sampleprobe arm assembly attached to the body, the sample probe arm assemblyincluding (1) a sample probe arm, (2) a hollow sample probe having aninternal chamber, an open lower end and an open upper end and (3) anelongate rotatable sample stirring rod having a lower end and an upperend, the lower end of the sample stirring rod including a samplestirring rod paddle attached thereto, the sample probe and the samplestirring rod being disposed generally vertically but angled inwardlytowards one another and being disposed in close proximity to oneanother, the sample probe being vertically movable between a lowersample probe position and an upper sample probe position, the samplestirring rod being movable independent of the sample probe between alower sample stirring rod position and an upper sample stirring rodposition, the sample probe and sample stirring rod being disposed withinthe sample probe arm assembly such that, when the sample probe is at thelower sample probe position and the sample stirring rod is at the lowersample stirring rod position, the lower end of the sample probe isspaced apart from the lower end of the sample stirring rod by a distanceof between about 1.7 and about 5.3 mm, the sample probe arm beingmovable between a first sample probe arm position wherein the sampleprobe is immediately above the sample extraction site and a secondsample probe arm position wherein the sample probe is immediately abovethe at least one cuvette mixing site; (f) a sample probe arm motor formoving the sample probe arm between the first sample probe arm positionand the second sample probe arm position; (g) a sample probe positioningmotor for moving the sample probe between the lower sample probeposition and the upper sample probe position; (h) a sample stirring rodpositioning motor for moving the sample stirring rod between the lowersample stirring rod position and the upper sample stirring rod position;(i) a sample stirring rod rotating motor for rotating the samplestirring rod; (j) a sample probe pressure altering assembly foralternatively applying a positive pressure and a negative pressure tothe interior chamber of the sample probe; (k) a reagent probe armassembly attached to the body, the reagent probe arm assembly including(1) a reagent probe arm, (2) a hollow reagent probe having an internalchamber, an open lower end and an open upper end and (3) an elongaterotatable reagent stirring rod having a lower end and an upper end, thelower end of the reagent stirring rod including a reagent stirring rodpaddle attached thereto, the reagent probe and the reagent stirring rodbeing disposed generally vertically but angled inwardly towards oneanother and being disposed in close proximity to one another, thereagent probe being vertically movable between a lower reagent probeposition and an upper reagent probe position, the reagent stirring rodbeing movable independent of the reagent probe between a lower reagentstirring rod position and an upper reagent stirring rod position, thereagent probe and reagent stirring rod being disposed within the reagentprobe arm assembly such that, when the reagent probe is at the lowerreagent probe position and the reagent stirring rod is at the lowerreagent stirring rod position, the lower end of the reagent probe isspaced apart from the lower end of the reagent stirring rod by adistance of between about 1.7 and about 5.3 mm, the reagent probe armbeing movable between a first reagent probe arm position wherein thereagent probe is immediately above the reagent extraction site and asecond reagent probe arm position wherein the reagent probe isimmediately above the at least one cuvette mixing site; (l) a reagentprobe arm motor for moving the reagent probe arm between the firstreagent probe arm position and the second reagent probe arm position;(m) a reagent probe positioning motor for moving the reagent probebetween the lower reagent probe position and the upper reagent probeposition; (n) a reagent stirring rod positioning motor for moving thereagent stirring rod between the lower reagent stirring rod position andthe upper reagent stirring rod position; (o) a reagent stirring rodrotating motor for rotating the reagent stirring rod; (p) a reagentprobe pressure altering assembly for alternatively applying a positivepressure and a negative pressure to the interior chamber of the reagentprobe; (q) a cuvette wash station attached to the body, the cuvette washstation including at least one hollow cuvette wash station probe havingan internal chamber, an open lower end and an open upper end, thecuvette wash station probe being vertically movable between a lowercuvette wash station probe position and an upper cuvette wash stationprobe position, the cuvette wash station being disposed such that thecuvette wash station probe is immediately above the cuvette washingsite; (r) a cuvette wash station probe positioning motor for moving thecuvette wash station probe between the lower cuvette wash station probeposition and the upper cuvette wash station probe position; and (s) acuvette wash station probe supply and disposal assembly foralternatively (1) providing pressurized washing liquid from a source ofwashing liquid to the cuvette wash station probe for washing a cuvettedisposed within the random access analyzing station at the cuvettewashing site and (2) providing a negative pressure to the internalchamber of the cuvette wash station probe for removing waste liquidsfrom a cuvette disposed within the random access analyzing station atthe analyzing site and for transferring such waste liquids to a disposalsite.
 2. The device of claim 1 wherein the sample probe and samplestirring rod are disposed within the sample probe arm such that, whenthe sample probe is at the lower sample probe position and the samplestirring rod is at the lower sample stirring rod position, the lower endof the sample probe is spaced apart from the lower sample stirring rodby a distance of between about 1.7 and about 3.5 mm, and wherein thereagent probe and reagent stirring rod are disposed within the reagentprobe arm assembly such that, when the reagent probe is at the lowerreagent probe position and the reagent stirring rod is at the lowerreagent stirring rod position, the lower end of the reagent probe isspaced apart from the lower end of the reagent stirring rod by adistance of between about 1.7 and about 3.5 mm.
 3. The device of claim 1wherein the sample probe and sample stirring rod are disposed within thesample probe arm such that, when the sample probe is at the lower sampleprobe position and the sample stirring rod is at the lower samplestirring rod position, the lower end of the sample probe is spaced apartfrom the lower sample stirring rod by a distance of between about 1.7and about 3 mm, and wherein the reagent probe and reagent stirring rodare disposed within the reagent probe arm assembly such that, when thereagent probe is at the lower reagent probe position and the reagentstirring rod is at the lower reagent stirring rod position, the lowerend of the reagent probe is spaced apart from the lower end of thereagent stirring rod by a distance of between about 1.7 and about 3 mm.4. The device of claim 1 further comprising a controller for controllingthe operation of the motors, analyzers and bar code readers.
 5. Thedevice of claim 4 wherein the controller comprises a digital computer.6. The device of claim 1 wherein the sample station comprises a rotatingsample carousel.
 7. The device of claim 6 wherein the sample carouselcomprises an exterior wall and a sample carousel retainer assembly forretaining a sample container rack, the sample container rack having asample container rack assembly for retaining a card displaying bar codedinformation.
 8. The device of claim 1 further comprising a samplestation bar code reader disposed proximate to the sample station suchthat the sample station bar code reader can read bar coded informationdisplayed on the sample station.
 9. The device of claim 7 furthercomprising a sample station bar code reader disposed proximate to thesample carousel such that the sample station bar code reader can readbar coded information displayed on a bar code containing card attachedto the sample container rack.
 10. The device of claim 8 furthercomprising a sample station bar code information computer assembly forreceiving and storing bar coded information read by the sample stationbar code reader and for issuing operating instructions to thecontroller.
 11. The device of claim 1 wherein the sample station issized and dimensioned to retain a plurality of diluent containers. 12.The device of claim 1 wherein the sample station comprises a pluralityof dilution cups.
 13. The device of claim 1 wherein the sample stationcomprises a plurality of dilution sections, each dilution sectioncomprising a plurality of dilution cups.
 14. The device of claim 12wherein the dilution cups each comprise a dilution cup narrow well. 15.The device of claim 14 wherein the dilution cup narrow wells eachdefines a volume of between about 10 microliters and about 100microliters.
 16. The device of claim 1 wherein the reagent stationcomprises a rotating reagent carousel.
 17. The device of claim 1 whereinthe reagent station is refrigerated.
 18. The device of claim 1 furthercomprising a reagent station bar code reader disposed proximate to thereagent station such that the reagent station bar code reader can readbar coded information displayed on the reagent station.
 19. The deviceof claim 18 further comprising a reagent station bar code informationcomputer assembly for receiving and storing bar coded information readby the reagent station bar code reader and for issuing operatinginstructions to the controller.
 20. The device of claim 1 wherein therandom access analyzing station comprises a rotating cuvette carousel.21. The device of claim 1 wherein the random access analyzing station isheated by the flow of upwardly directed heated air.
 22. The device ofclaim 1 further comprising a first light source disposed proximate tothe random access analyzing station for directing a beam of lightthrough the cuvettes.
 23. The device of claim 22 wherein the first lightsource is a laser.
 24. The device of claim 22 further comprising asecond light source disposed proximate to the random access analyzingstation for directing a beam of light through the cuvettes.
 25. Thedevice of claim 23 wherein the first light source is a visible diodelaser emitting light at a wavelength between about 600 and about 850 nm.26. The device of claim 24 wherein the second light source is a lightemitting diode capable of emitting light at a wavelength between about850 and about 1050 nm.
 27. The device of claim 1 further comprising anonboard control sample disposed within the random access analyzingstation.
 28. The device of claim 1 wherein the sample probe is attachedto the sample probe arm with a rack and pinion assembly for raising andlowering the sample probe and wherein the sample stirring rod isattached to the sample probe arm with a rack and pinion assembly forraising and lowering the sample stirring rod.
 29. The device of claim 1wherein the sample stirring rod is disposed at a angle with respect tothe sample probe of between about 2.4 and about 2.6 degrees.
 30. Thedevice of claim 1 wherein the sample probe and reagent probe pressurealtering assemblies both comprise a syringe.
 31. The device of claim 1wherein the cuvette wash station comprises two concentric hollow cuvettewash station probes, each such probe having an internal chamber, an openlower end and an open upper end.
 32. The device of claim 1 wherein thecuvette wash probe supply and disposal assembly includes a waste trapassembly comprising:(a) a waste trap reservoir having an upper portionand a lower portion; (b) a waste collector bowl disposed below the wastetrap reservoir; (c) a vertically disposed connector conduit forconnecting the waste trap reservoir in fluid communication with thewaste collector bowl, the connector conduit having an uppermost lip overwhich waste liquids within the waste trap reservoir can spill over intothe waste collector bowl; (d) a connector conduit check valve forpreventing the upward flow of liquids and pressurized air within theconnector conduit from the waste collector bowl to the waste trapreservoir; (e) an inlet port in the upper portion of the waste trapreservoir for receiving waste liquid from the cuvette wash stationprobe; (f) an outlet port in the bottom of the waste collector bowl fordraining liquid within the waste collector bowl to a suitable wastedisposal facility via a drain conduit; (g) a drain conduit check valvedisposed within the drain conduit to prevent liquids to flow into thewaste collector bowl via the drain conduit; (h) a level sensor forsensing the level of liquid within the waste collector bowl and emittinga corresponding level sensor signal; (i) a switch assembly foralternatively applying pressure and vacuum to the waste collector bowl;(j) a waste trap controller for receiving the level sensor signal fromthe level sensor and therewith controlling the application of vacuum andpressure to the waste collector bowl in such a way that (i) when thelevel of liquid within the waste collector bowl is below a preselectedset point, vacuum is applied to the waste collector bowl to draw wasteliquid from the waste trap reservoir and (ii) when the level of liquidwithin the waste collector is at the preselected set point, pressure isapplied to the waste collector bowl to blow down waste liquid within thewaste collector bowl to the drain conduit.
 33. The device of claim 32wherein the waste trap assembly connector conduit check valvecomprises:(a) an inlet conduit; (b) a valve seat disposed below theinlet conduit and in fluid tight communication therewith; (c) an outletconduit disposed below the valve seat and in fluid tight communicationtherewith; (d) a plug loosely disposed within the valve seat such that(1) when the pressure within the inlet conduit is equal to or greaterthan the pressure within the outlet conduit, the plug is not heldtightly against the valve seat so as to allow liquid waste within theinlet conduit to gravitate into the outlet conduit and (2) when thepressure within the inlet conduit is less than the pressure within theoutlet conduit, the plug is held tightly against the valve seat so as toprevent liquid waste within the inlet conduit from gravitating into theoutlet conduit and to prevent pressurized air in the outlet conduit fromflowing through the inlet conduit into the waste trap reservoir.
 34. Thedevice of claim 33 wherein the plug is a flexible disk.
 35. The deviceof claim 33 wherein the plug has a central aperture which is offset fromthe inlet conduit.
 36. The device of claim 33 wherein the switchassembly comprises:(a) a vacuum source inlet port disposed in the wastetrap reservoir, the vacuum source inlet port being connectable to asource of vacuum; (b) a three way valve having a common port, a normallyopen port and a normally closed port; (c) a first pressure sourceconduit connected in fluid tight communication between the common portand the waste collection bowl; (d) a second pressure source conduitconnected in fluid tight communication between the normally open portand the waste trap reservoir; and (e) a third pressure source conduitconnected in fluid tight communication between the normally closed portand a source of air pressure.
 37. A device for determining at least oneparameter of a liquid, wherein the device comprises at least one movableprobe arm assembly adapted for extracting liquids from a first vessel,depositing those liquids into a second vessel, and stirring the contentsof the second vessel, the probe arm assembly comprising (1) a probe arm,(2) a hollow probe having an internal chamber, an open lower end and anopen upper end and (3) an elongate rotatable stirring rod having a lowerend and an upper end, the lower end of the stirring rod including astirring rod paddle attached thereto, the probe and the stirring rodbeing disposed generally vertically but angled inwardly towards oneanother and being disposed in close proximity to one another, the probebeing vertically movable between a lower probe position and an upperprobe position, the stirring rod being movable independent of the probebetween a lower stirring rod position and an upper stirring rodposition, the probe and stirring rod being disposed within the probe armassembly such that, when the probe is at the lower probe position andthe stirring rod is at the lower stirring rod position, the lower end ofthe probe is spaced apart from the lower end of the stirring rod by adistance of between about 1.7 and about 5.3 mm.
 38. The device of claim37 wherein the probe is attached to the probe arm with a rack and pinionassembly for raising and lowering the probe, and wherein the stirringrod is attached to the probe arm with a rack and pinion assembly forraising and lowering the stirring rod.